rs485 or CAN or ?? industerial network

[7rots51]

hello

Is this correct?
if one RS485 driver IC in a card failed(in a RS485 network) then the total network will fail! because it may drive the network in failed condition.

Network?
For Industerial networking and ranges up to 1000 meter and speeds up to 115200 kbps which system is better ? RS485 ,CAN or other ones?please specify the benefits of each one and their weak points.

bye

 

[techie]

R-485 is by far the most cost effective. The network does not go down if one of the chips fail. Except in a rare event when the chip short circuits the two data lines. But 485 does not offer any isolation in itself. So dangerous voltage levels that develop across the network might fry the electronics. It is more than suitable for 115kbps over the 1000m range.

You could use ethernet if the cost allows. The best thing about this network is its built in isolation. But thereare other issues to look at as well. In these times, the 10-baseT requires a star t oplogy so the wiring is quite extensive if you have more than a few stations.

I have not used CAN bus, sorry.

 

[7rots51]

hello
Is there a bus other than CAN or RS485 that can send data up to 3000 meter with 12kbit/sec?

bye

 

[trace_ru]

CAN is bar far the most reliable of these two. But, as it has been mentioned before, RS485 is the cheapest. Frankly, everything depends on the task.
You've got to remember that CAN is a message-based network. I.E. we are talking just messages sent and received by nodes. But the advantages are very high reliability, speed and, of course, hardware implementation in ICs.
I have done ome projects with RS485 but am starting a new one with CAN which looks great to me.
trace

 

[hock]

use CAN or ethernet for your network.
they are the best for this purpose.
hock

 

[sklux]

hello
Is there a bus other than CAN or RS485 that can send data up to 3000 meter with 12kbit/sec?

bye

dont mix RS485 and CAN :

RS485 is an hardware protocol
CAN is a software protocol
so you can have CAN on RS485.

In fact many industrial protocol can be used with lenght of 3000 meter
using repeaters.

check Profibus-Fipway or Ethernet

 

[neuralc]

HI all,

Does anyone know a IC (cheap!) that gives some kind of ethernet interface with a microcontroler?


NeuralC

 

[silvio]

Hi neuralc,

Hope you're concerned to CAN interface rather than RS485.
A stand alone CAN controller which can be connected with a microcontroler is Philips SJA1000 the successor of the PCA82C200. Obvious for microcontroller which don't include CAN by default. You must provide the interface between the CAN protocol controller and the physical bus, too.

**broken link removed**

Silvio

 

[7rots51]

hi

I need to know is there a network physical layer like as ethernet or RS485 that I can use it for 3000 meter or above without repeater at 128kbit/sec?

Can I use Bus isolation in CAN?

bye

 

[gabby]

Hi 7rots51.

8O 3000meter or more is a long of way for industrial line network.
Most solutions that you are looking for them like rs485, can ...
are for more low distance.

For the distance you are looking in phisical line try some solutions
form the telephony central interface like: fiberoptics , T1/E1 , ISDN , ADSL....

Best regards Gabby. 8)

 

[silvio]

Yes, sklux points out very well. At least for what he has in mind.
Because like most of us he still uses generic terms.

He said:
RS485 is an hardware protocol.
CAN is a software protocol.

Correct it should be:

RS485 (EIA/TIA 485) is an hardware interface not hardware protocol. RS485 has nothing to do with term protocol. Without a special network software, RS485 it's useless, because it's simple driver not a protocol.
CAN is indeed a software protocol, though most of us uses generic term CAN when thinking about the composed software protocol + controller + hardware interface.

Since RS485 it's a balanced driver it could be used as interface for CAN controller as well, exactly mentioned by sklux.

I failed in the same trap like others.
Even neuralc ask:
Does anyone know a IC (cheap!) that gives some kind of interface with a microcontroler?

First of all what some kind of interface ?
1.Standard EIA/TIA 485 (i.e. 75176)? If yes, what kind of software network protocol ?
2.Standard CAN interface (i.e. Philips PCA82C250 )?

Cheap ?
Take a pencil, sit down and writes all your requirements.
For reference you can take a look at i.e Maxim web site and see what are the basic criteria for spliting the 485 product range.
As long as the choosen product covers most of your common design requirements, it's cheap.


Silvio

 

[neuralc]

Sorry, I miss Ethernet interface chip...

 

[silvio]

Hi neuralc,

Hope you expected to spell RTL8019AS, but it's the cheapest I know, besides it's widely available. Even if was developed for ISA bus you can easily attach to microcontroller.

Silvio

 

[hock]

maxim has a new 8051 chip which has ethernet built in to it

also some one has asked if can can be used in isolated mode
yes it can be, go to CIA site ot bosh site for details

hock

 

[neuralc]

Hi silvio,

RTL8019 looks like a good choice, only problem is QFP100 package. But I have tried to look a place to buy it (like Farnell) and I'm unable to find it, do you know a place to buy small quantities?(and the average price of it)

Here is a site given a simple explenation of how to interface it with 8051 controler:
**broken link removed**

ThX

NeuralC

 

[7rots51]

hello
what about my question?
Is there a physical layer that I can send data through it at 128kbit/sec without repeater at 2000 meter scale at least?
Is RS485 suitable for this?

bye

 

[silvio]

Hi neuralc,

For small quantity including Xtal and RJ-45 Connector with 10Base-T transformer you can take a look at:
**broken link removed**

If QFP100 package scared you and if don't find a good solution (call it cheaper ) to solderize it on prototype board, buy one piece from www.edtp.com. There you can find a good solution for 8051 RTL8019AS tandem. It's call Whacker 8051. For the components included it's a real bargain.

For the same tandem included on one board you can look at:
**broken link removed**
There you can find software solutions, too.

Silvio

 

[cdcll]

hello
what about my question?
Is there a physical layer that I can send data through it at 128kbit/sec without repeater at 2000 meter scale at least?
Is RS485 suitable for this?

bye

I think both RS485 and current loop can meet your requirement.

 

[silvio]

If you don't like hardware solutions from Dallas / Maxim for TCP/IP stack you can try from:

http://www.century-semi.com/CS6208.html
**broken link removed**

They provides a development board ( $100 ) and what it's really nice, together with an ICE board for debug purpose using the K_e_i_l Ews-u*Vision*2 in-system-debugger.
Another manufacturer which uses the CS6208 for development board you can find here:
**broken link removed**

Silvio

 

[silvio]

Hi 7rots51,

It's not a nice behaviour from us to change slightly the purpose of the thread you started.

Thus answers to your question are easy to find on maxim site. They provides nice hints for applications developers.

Bellow are some of most interesting for you.

Most RS-485 users want to know the answer to one crucial question: How far can you reliably transmit and receive data at a specified data rate? RS-485 transceivers operate across 4000ft and at 10Mbps, but not at the same time. The trade-off has always been less distance at a higher rate or greater distance at a lower rate
More about Distance versus Data Rate and Pre-Emphasis technique at:
**broken link removed**

Guidelines for Proper Wiring of an RS-485 (TIA/EIA-485-A) Network **broken link removed**
Explanation of Maxim RS-485 Features **broken link removed**
RS-485 Data Interface Gives Isolated, Full-Duplex Operation **broken link removed**
Using RS-485/RS-422 Transceivers in Fieldbus Networks **broken link removed**
Microcontroller Recognizes Addresses in RS-485 Systems **broken link removed**


What the Data Sheet Doesn't Tell You

Deciding whether you need a termination resistor or not is only part of the problem in implementing an RS-485 system
More about that on Selecting and Using RS-232, RS-422, and RS-485 Serial Data Standards **broken link removed**

A good source of information regarding 485 is:
**broken link removed**
It's recommended by Maxim in one of their application notes, too.

Silvio